The present invention relates to vehicle diagnostic systems and methods, and, more particularly, to devices and methods for adaptively accessing vehicle diagnostic information in a manner to avoid engine specific anomalies.
Since the 1980's, major automobile manufacturers have installed electronic control units (ECU) in vehicles being produced. ECU's generally function to monitor various vehicle conditions and recognize malfunctions or trouble conditions, which may be recorded in the vehicle ECU. Technicians servicing the vehicles have used scan tools, or other equipment that enables them to access the ECU to download vehicle diagnostic trouble codes (DTC's) that would identify the malfunctions or trouble conditions detected by and stored in the ECU.
Since the 1980's, the sophistication of the vehicle ECU's, scan tools and other equipment used to access information in the ECU's has become more sophisticated. The vehicle information accessible by or through the ECU has expanded to include a variety of different types of information, e.g., live information and/or stored information from various vehicle components. Moreover, the processing capability of the ECU, as well as the scan tool, have expanded to allow the technician to more specifically identify vehicle defects by accessing and comparing information received from the vehicle, using sophisticated databases that may be stored or distributed within the ECU, the scan tool, and remote locations, e.g., websites accessible by the scan tool itself, or in association with a digital computing device, such as a computer or cellphone.
In order to facilitate the use of common equipment and communication techniques for accessing information on different vehicles, vehicle original equipment manufacturers (OEMs) utilize one of approximately five different signal protocols for communicating information and commands to or from the ECU. Contemporary scan tools and similar devices commonly connect to the ECU through a vehicle diagnostic port, and operate to poll the ECU, by sequencing through each of the different protocols until the ECU response to one of the protocols. The scan tool will then communicate with the ECU in the identified protocol to request information from the ECU and other vehicle systems.
While the above described ECU interface system generally works well and is a reliable way to access information from the vehicle ECU, anomalies occasionally arise in relation to particular engines. For example, it has been found that certain Ford® vehicles equipped with 7.3 L diesel engines will stall if certain diagnostic information is requested from the vehicle ECU while the vehicle is running, e.g. engines and related electronic controls for the engine are understood to have been produced by Navistar International (engine code T444D) during 1994-2003. This can create a safety condition, particular as that vehicle may be used to tow excessive loads. Since the functionality of hydraulic power assisted braking (Hydro Boost) systems and steering systems are generally dependent upon the engine being operational, a sudden engine stall can be problematical. While OEMs generally take steps to ensure that power and fluid remains available in the event of such a stall, the stored power and fluid under pressure may be very limited, e.g., to power assisted brake applications, which may be insufficient to avoid a dangerous and potentially fatal condition.
The present invention is directed to an apparatus and technique for modifying the manner in which a scan tool, or other diagnostic device, communicates with a vehicle ECU to determine if the vehicle under test is subject to causing an operational anomaly in response to a standard information requests to the vehicle ECU. If so, the present invention functions to modify the information requests in such a manner to be able to avoid the anomaly, i.e., by omitting or modifying the information request that has been found to trigger the anomaly.